1. Field of the Invention
The present invention relates to an electronic musical instrument and, more particularly, to an electronic musical instrument capable of compressing waveform data for storage and reading out the stored data in any reading scheme.
2. Description of the Related Art
In a conventional synthesizer, an electronic piano, an electronic organ, an electronic single keyboard, and other electronic musical instruments, a musical tone generated by an acoustic musical instrument is recorded (as in PCM recording, for example) from the beginning of sound to the end thereof or up to a point at which there is little change in timbre, the recorded sound is processed so as to have desired characteristics, and the resultant waveforms are stored in a waveform memory. In reproduction, the stored data is read out of the memory at an address interval corresponding to the pitch for a pressed key, an envelope is given to the read data, and the enveloped data is sounded. Also, other sounding processing operations are practiced in a manner which the last half of a tone waveform is repeatedly read in the forward direction or in the backward direction, or in an alternate manner in which particular waveform ranges are read in both the directions alternately.
However, in the waveform storing system in the conventional electronic musical instruments, the sampled values themselves of a PCM-recorded waveform are stored over a plurality of periods, thereby requiring the waveform memory of a relatively large capacity.